The long-term objective of this research project is to improve our ability to design effective treatment strategies for the remediation of cognitive impairments in general, and aphasic symptoms in particular. The project examines a specific design variable that has application to many kinds of cognitive rehabilitation programs - the extent to which the patient makes errors when attempting to produce the correct response during training. The project focuses on one particular cognitive deficit, anomia, in attempting to study the relative efficacy of errorless vs. errorful learning in the rehabilitation of cognitive deficits. Anomia, an impairment in the retrieval of words, is the most common deficit resulting from a left hemisphere stroke. This deficit can have grave consequences upon one s ability to communicate effectively, and can interfere with work, social function, and everyday life. A specific aim of the project is to test the hypothesis that patients with anomia subsequent to stroke are more likely to improve their ability to retrieve words following a therapy that allows for few or no errors during training compared with a commonly used therapy that guarantees that errors will be produced. A second aim is to examine the effects of intact vs. impaired explicit learning on the effects of the errorless/full variable. Both of these hypotheses derive from the literature on errorless vs. errorful learning that has been applied to patients with memory deficits. Patients with anomia will participate in a therapy program in which two different sets of words are trained under different conditions. In the errorful condition, the patient first attempts to name a picture without any external cues. If an incorrect response is produced, a cue of minimal stimulus power is provided. If another incorrect response is given, a more powerful cue is added, etc, until the patient produces the correct word. In the errorless condition, the patient views a picture and is given its name, both in writing and orally, and is asked to reproduce it. Pieces of the word are then removed bit by bit, and the patient names the item after each successive piece is removed. The conditions will be compared, within-subject, for differences in time to learn the words and degree of retention of the words learned after one month. These results will be correlated with the results of a test of explicit learning. The overall results will provide the basis for future studies of the importance of the errorless/ful variable in the design of cognitive rehabilitation of other cognitive deficits, and the potential value of tests of explicit learning in predicting therapy success.